The relationship between stand structure of Calluna vulgaris and the ability of Betula spp. to establish was examined at Dinnet Moor, Aberdeenshire. As a result of management by burning, a series of even-aged stands of Calluna is available including recently-burnt examples and stands with Calluna in the pioneer, building, mature and degenerate phases. Uneven-aged stands were included for comparison. The density of birch was found to be high very shortly after burning, much less in pioneer phase stands and minimal in the building and mature phases, indicating high mortality as the stand ages. Some indication of slightly higher densities in degenerate stands was obtained, suggesting some recruitment at this stage. Comparisons of the age of individual birches (seedlings or saplings) with that of the adjacent Calluna showed that, in general, birch is established very shortly after Calluna begins to regenerate, the surviving birch individuals being consistently one or two years younger than the Calluna. Again, results indicated little or no recruitment after the Calluna stands enter the building phase. Experimental introduction of birch seedlings to stands of various age since burning showed that survival and performance was best in the pioneer stands, and poorest in building stands.
It is concluded that birch is virtually excluded by dense Calluna stands in the building and mature phases, and that carefully controlled management involving regular burning may therefore prevent the entry of birch. However, occasional fires followed by slow or patchy Calluna regeneration may provide ideal conditions for birch establishment.